Lifting-jack.



F. C. SPENCER;

LIFTING JACK. APPLICATION FILED SEPT- I 5, 1915.

l 1 75,5 69 Patented Maf. 14, 1916.

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'me COLUMBIA xLANoGnAPu C0.. WASHlNTON, D. c.

FREDERICK C. SPENCER', OFGUILFORD, CONNECTICUT.

` marine-JACK.

Specification of Letters Patent.

Patented Mar. 14e, 1916.

Application led. September 15, 1915. Serial No. 50,763.

To all whom t may concern:

Be it known that I, FREDERICK C. SPENCER, a citizen of the UnitedStates, and resident of Guilford, in the county of New Haven and Stateof Connecticut, have invented a new and useful Improvement in Lifting-Jacks, of which the following is a specification.

My invention relates to an improvement in lifting jacks with the objectin view of providing means for preventing the backward movement of thepinion nut when the Operating lever is swung back.

A practical embodiment of my invention is illustrated in theaccompanying drawings, in which,

Figure 1 is a view of the jack in side elevation, the operating leverbeing shown in full lines out of operative position, and in dotted linesin operative position. Fig. 2-is a vertical central section, Fig. 3 is atransverse section in `the plane of the lineA-A, Fig. 1, and Fig. t is atransverse section in the plane of the line B-B, Fig. 1. y

The general construction of the jack is quite similar to the structureof the jack shown, described and claimed in Letters Patent No.1,148,868, granted to me on the 3rd day of August, 1915, and need not beparticularly described herein.

The pedestal is denoted by 1, the pawl carrying ring mounted on thepedestal yby 2, the double-acting pawl by 3, lthe lifting screw by 4,the pinion nut engaged with the screw by 5, and the operating leversuspended from the'pawl carrying ring 6.

It has been found inpractice necessary toy hold thepinion nut 5 with onehand, againstv a return movement while theyotherhand was working theoperating lever, until suoli time as the weight on the lifting screwproduced sufficient friction to hold the nut. This use` of both hands onthe jack when the body of 'the operator is in the awkwardor crampedposition commonly assumed under a motor car, 1s inconvenient andannoyingy and it is to remedy this-inconvenience and annoyance that mypresent invention is made. y

The, pedestal l is provided conveniently on the side opposite that onwhich the operating lever is normally located, with an upwardlyextendingarm 7. At a point opposite the teeth on the nut 5, the arm 7 is providedwith a bore 8 in which is freely mounted a dog 9, the inner end of whichis in position to engage the teeth on the nut 5, and the outer end inposition to be pressed upon by the free end of a spring strip 10,secured at its lower end to the arm 7, in the present instance by ascrew l1. The dog 9 is preferably made cylindrical so that it may rotatefreely in the bore 8, as well as slide longitudinally therein, and itsinner end is made in a blunt conical shape so that it will present thesaine degree ofy inclined obstruction to the teeth of the nut, whateverbe its rotary adjustment in its bore. This will prevent the dog vfromirregular wear as it will be free to present a new surface to the teethat each step of rotation of the nut. The spring tension onthe dog isintended to be just sufficient to prevent a backward movement of the nutwhen the lever is returned for a new stroke, and the dog will sli deover the teeth of the nut as the nut is forcibly turned by the operatinglever.

lVith this constructioi'i only one hand of the operator is required tooperate the jack even before the weight of the object to beV lifted isexertedV on the jack andl its practical efliciency is thereby materiallyimproved.

What I claim is:

1. In combination with a pinion nut, a lifting screw with which the nutis engaged, a Support for the nut and means for operating it, a yieldingdog having a tapered end in position to engage the teeth on the pinionnut to hold it against an unintentional backward movement whilepermitting it forced movement.

2. In combination` with a pinion nut. a lifting screw with which the nutis engaged,

a support for the nut and means for oper ating it, a longitudinallyyielding rotary dog having a tapered end in poistion to engage the teethof the nut to prevent unintentional movement of the nut while permittingintentional movement of the saine.

y 2 Y Y 1,175,569

3. In combination 'with a pinion nut,' a spring for forcing the dog intoengagement lifting screw With which the nut is engaged, With the teethof the nut.V a support for the nut provided with an arm n In testimonythat I claim the foregoing 10 extending upwardly therefrom,v the said asmy invention, I have signed my name 5 arm provided with a bore oppositethe nut, this 4th day of September, 1915.

and means for operatingV the nut, a rotary Y l dog seated in the bore inthe armyand a FREDERICK C.v SPENCER?.-

Copies of this'patent mayY he Vobrtanedjfor vejcents each, by addressingthe Commissioner of Patents,

Washington, D. C. Y

